The present invention relates generally to printing presses and more particularly to angle bars for web printing presses.
U.S. Pat. No. 5,464,143 discloses a width adjustable angle bar assembly for a printing press. The adjustable angle bar assembly has a support and a hollow angle bar pivotally mounted adjacent a central portion of the angle bar. The angle bar may be moved between first and second separate positions approximately ninety degrees apart. As shown in the figures, the support and pivot point for the angle bar is off-center from the web, so that reversal of the angle bar requires realignment of the web to a new centerline.
An object of the present invention is to provide a reversible angle bar device in which the centerline of the web does not vary in either position of the angle bar. Another alternate or additional object of the present invention is to provide a reversible angle bar which is easy to reverse.
The present invention provides a reversible angle bar device for a web printing press having a web with an entering web centerline. The angle bar device includes a support, a first angle bar portion angled with respect to the first entering web centerline on a first side of the entering web centerline, a second angle bar portion angled with respect to the entering web centerline and being located on a second side of the entering web centerline opposite the first side, the first and second angle bar portions being fixed to the support, and a moveable angle bar portion selectively attachable to either the first angle bar portion or the second angle bar portion.
By providing a movable angle bar portion and two fixed angled angle bar portions, a reversible angle bar device may be provided in which the web centerline does not vary relative to a support centerline. A robust design with high accuracy, speed and repeatability is thus also possible.
Preferably, the first angle bar portion has an angle of 45 degrees to the entering web centerline, as does the second angle bar portion, the first and second angle bar portions thus being angled at 90 degrees to one another.
The first and second angle bar portions preferably are symmetric to one another about the entering web centerline.
The moveable angle bar portion may be attached to either the first or second angle bar portion in an air-tight manner using for example a sliding fit, a screw fit, or a self-locking mechanism. An air supply is connected to both the first and the second angle bar portions.
The support may be movable.
The angle bar device thus provides a first exiting web position and a second exiting web position in which the first exiting web centerline and the second exiting web centerlines are the coextensive. An effective pivot point of the two angle bar positions thus may be defined, the pivot point being on the entering web centerline on a longitudinal axis of the angle bar at a location closer to the entering web than the first and second exiting web centerlines.
The present invention thus also provides a reversible angle bar for a web having an entering centerline, the device comprising an angle bar having a first position with a first exiting web centerline and a second reversed position with a second exiting web centerline coextensive with the first exiting web centerline, the reversible angle bar having a longitudinal axis and having an effective pivot point located on the longitudinal axis and on the entering web centerline closer to the entering web than the first and second exiting web centerlines.
The present invention also provides a method for changing a direction of a web exiting an angle bar device comprising the steps of: sending a web having an entering web centerline over an angle bar device in a first position and exiting the web at a first exiting web centerline, the first exiting web centerline being at an angle to the entering web centerline; changing the first position of the angle bar device to a second position; and sending the web at the entering web centerline over the angle bar device in the second position and exiting the web at a second exiting web centerline, the second web centerline being at another angle to the entering web centerline.